What was going on when I was born?

American Brands Inc., the nation's oldest tobacco company, is sitting on so much money these days that it can afford to be patient. When Norton Simon Inc. went on the auction block, American Brands was approached by investment bankers who knew the diversified tobacco company had cash and credit of more than $2 billion for non-tobacco acquisitions. And when Stokely-Van Camp Inc. was looking for a friendly company to save it from a takeover by the Pillsbury Company, Stokely's investment bankers also came to American Brands. American Brands passed in both cases.

''As the investigation of Klaus Barbie has shown, officers of the United States Government were directly responsible for protecting a person wanted by the Government of France on criminal charges and in arranging his escape from the law.'' - Allan A. Ryan Jr., a Justice Department official. (A8:1.)

International U.S. Army officers hid Klaus Barbie after World War II, according to the Justice Department. The department, after a five-month investigation, said that counterintelligence officers had hidden Mr. Barbie, a former Gestapo officer wanted by the French for war crimes, employed him as a spy in Germany and then helped him escape to Bolivia in 1951. The report concluded that Army officers had lied to American civilian authorities to hide the high Nazi official, who is now being held in a Lyons prison. (Page A1, Columns 1-2.) France has expressed irritation at American pressure on Paris to intervene in the war in Chad. In addition, President Francois Mitterrand said he sent troops to Chad to prod Libya to reach a negotiated settlement of the war, believing that a military solution was impossible. (A1:3-4.)

THEY began some 50 strong, song sheets in hand - by belting out all four choruses of ''There's No Business Like Show Business'' in front of Mays department store on 14th Street at Broadway. Mays was once the site of the Union Square Theater and this was, officially, a sing-along salute to celebrate the 250th anniversary of the New York stage. Unofficially, it was an opportunity for would-be warblers to come out of the shower. Or, as Felix Cuervo announced over his bullhorn, ''This is a chance to be happy and have a good time.'' Mr. Cuervo, a retired civil service worker and president of the Native New Yorkers' Historical Association, was the leader of last Sunday's musical excursion to famous theatrical sites north of 14th Street. He said records show that the first stage performance in America was given in Lower Manhattan 250 years ago. The celebration was sponsored by the 92d Street Y and the charge of $6.50 included the lyrics to 33 songs. A few minutes after 11 A.M., the group trooped around the corner to the spot where Wallack's Theater once stood and sang ''Oh, How I Hate to Get Up in the Morning.''

Marc Rich & Company A.G., the Swiss-based commodity trading firm under investigation for possible United States tax evasion, is in a classic double bind. The company cannot give American prosecutors many of the documents they have subpoenaed because the Swiss Government has seized them to make sure their release would not violate the corporate secrecy laws of Switzerland. But every day that goes by without Marc Rich turning over the documents means that it must pay another $50,000 fine because it is in contempt of court in the United States. Some Marc Rich documents, two trunks full, were seized in New York by American authorities.

Last Thursday, arsonists destroyed the sanctuary of a synagogue here. On Monday, several fires were set in the chapel and sanctuary of a second synagogue. Today, another fire destroyed the library of a rabbi's home. And this morning, as the state police and arson squads from the state and city searched through charred lumber, Jewish residents gathered in front of the rabbi's house to talk, to comfort one another and to search for an explanation of violence many said they felt was directed at them. State and local officials issued statements of outrage and joined forces to investigate the fires, which the police said had been deliberately set. Officials said they believed all three incidents were linked. Chief Francis Reynolds of the West Hartford police, said, ''I think it's linked to the same person.''

John D. Simpson, saying he had given ''everything I've got'' to the city's ailing subway and bus system, resigned unexpectedly yesterday as president of the New York City Transit Authority. The 46-year-old Mr. Simpson spoke of ''intractable'' problems on the subways, of the ''daily hammering'' by critics and of his desire to spend more time with his family. ''For the sake of my family and myself - and, I believe, for the good of the institution - four years is enough,'' Mr. Simpson said. His Plans Still Uncertain Mr. Simpson said he had not decided what to do next, but added, ''I do not think it will be in the public sector.''

In yet another August that marks the anniversary of its defeat in World War II, Japan is caught in an intense debate over whether it is time to assert itself actively once again in world affairs. A growing number of Japanese believe the country should carve out a military and diplomatic role equal to its obvious economic strength. This would require a great shift, both of resources and attitude, for a nation that has left global burdens to others while it concentrated on business. In the only country that has had atomic bombs dropped on it, there are even a few writers and academic figures who argue that acquisition of a nuclear force is long overdue. On the other side, still a majority, are those who fear than an active Japan would revert to the extreme nationalism that led to debacle in 1945. Pacifist strains run deep, as does a sense that Japan, as a defenseless nation, should not risk offending anyone because it depends on international trade for survival. For every advocate of nuclear weapons, there are probably several proponents of total disarmament.

The United States said today for the first time that the Army had hidden Klaus Barbie, a former Gestapo officer wanted by the French for war crimes, employed him as a spy in Germany and then helped him escape to Bolivia. The chief White House spokesman, Larry Speakes, said that a formal note expressing the ''deep regrets'' of the United States for the concealment of Mr. Barbie was delivered by the State Department to the French Embassy Friday. It was the first official admission by the United States that the Army had helped Mr. Barbie avoid prosecution and had employed him for its own purposes. Mr. Barbie has been called the ''butcher of Lyons'' for his activities in that French city during World War II. Five-Month Investigation The findings were in a 218-page report issued today by the Justice Department. The report concluded a five-month investigation ordered by Attorney General William French Smith in response to charges raised in France and the United States that Mr. Barbie had been employed as a spy by American intelligence officials and that he received American assistance in escaping to Bolivia in 1951.

Industrial production jumped 1.8 percent in July, the Federal Reserve reported today. The increase was led by a sharp rise in auto output and demand for electricity for air conditioning. The increase suggests that the recovery in the third quarter this year could be almost as strong as in the second quarter, when the gross national product soared at an annual rate of 8.7 percent after adjustment for inflation. Most economists do not expect this rapid expansion of the economy to continue; indeed they would be concerned if it did. With sustained growth at the pace of the second quarter, the economy would likely begin to overheat, putting upward pressure on prices and reigniting inflation sometime in 1984.

With the strike against the American Telephone and Telegraph Company in its second week, telephone equipment manufacturers who depend heavily on the continued health of the Bell System say the walkout is already hurting their operations. For most consumers, who use the highly automated parts of Bell's switching systems to complete their calls, the effects of the strike have so far been almost unnoticable. But for companies dependent on A.T.& T. personnel to connect them into the Bell network, and for those who supply Bell with cable, electronics and computer systems valued at millions of dollars, the walkout of 675,000 workers is already having a strong ripple effect. Yesterday, the Rolm Corporation, one of the nation's largest manufacturers of private branch exchanges, the switching systems used in most offices, indicated it could number among the strike's first casualties.

CERTAIN foods, like certain people, are intimidating merely because of their appearance - even before you know the first thing about them. A galantine of chicken or an airy mille- feuilles pastry, for example, look as if they require painstaking work; they do. Elegantly presented cold mousses of fish, fowl or seafood, which are so delightful this time of year, also look arduous; they are not. Food processors and blenders have eliminated the age-old necessity of pressing fish over a screen time and again to reach the right consistency for a mousse. Some may still grumble that food processors depersonalize the fine art of making mousses, but that is something like Egyptian slaves whining that the invention of the wheel, which obviated dragging 20-ton granite slabs across the desert, somehow cheapened the Pyramids. Cold mousses can be made with many kinds of seafood, meat and vegetables, or various combinations; once you understand the basic technique, variations in seasonings and presentation are unlimited.